2-(4-Hydroxy-4-methylpentyl)norbornadiene and process for preparing same

ABSTRACT

The novel compound, 2-(4-hydroxy-4-methylpentyl) norbornadiene, process for preparing said compound comprising the steps of: I. EFFECTING A REACTION BETWEEN CYCLOPENTADIENE AND A 5-HALO-1PENTYNE TO FORM A 2-(3-HALO-1-PROPYL)-2,5-NORBORNADIENE; II. REACTING THE HALOPROPYL NORBORNADIENE WITH MAGNESIUM TO FORM A Grignard reagent; III. REACTING THE Grignard reagent with acetone to form a Grignard complex; and IV. HYDROLIZING THE COMPLEX TO YIELD THE DESIRED PRODUCT. 2-(4-HYDROXY-4-METHYLPENTYL) NORBORNADIENE PRODUCES IN FOOD FLAVORINGS THE AROMA OF FULL RIPENED RASPBERRIES WITH THE TASTE OF THE RIPE RASPBERRY AND ITS SEEDY, RASPBERRY KERNEL NOTE.

United States Patent {I91 Sanders et al.

l i 2-(4-HYDROXY-4-METHYLPENTYL)NOR- BORNADIENE AND PROCESS FORPREPARING SAME [75] Inventors: James Milton Sanders, Eatontown; ManfredHugo Vock, Locust, both of NJ.

[73] Assignee: International Flavors & Fragrances lnc., New York, NY.

221 Filed: Jan. 7, 1975 [21] Appl. No.: 539.093

Related U.S. Application Data [62] Division of Ser. No. 46]]03, Aprill7, 1974, Pat.

[ Oct. 7, 1975 Primary Examiner-James 0. Thomas Jr.

Assistant E.xaminerlames H. Reamer Attorney, Agent or FirmArthur L.Lihcrman Esq; Harold Haidt, Esqv [57] ABSTRACT The novel compound2-(4-hydroxy-4methylpentyl) norbornadiene, process for preparing saidcompound comprising the steps of:

i. effecting a reaction between cyclopentadiene and a S-halol -pentyneto form a 2(3-hal0-1 pr0pyl)-2 5-norbornadienc; ii. reacting thehalopropyl norhornadiene with magnesium to form a Grignard reagent; iii.reacting the Grignard reagent with acetone to form a Grignard complex;and iv hydrolizing the complex to yield the desired product2-(4-hydr0xy-4 methylpentyl) norhornadiene produces in food flavoringsthe aroma oi full ripened raspberries with the taste of the riperaspberry and its seedy, raspberry kernel note.

1 Claim, No Drawings 2(4-l-lYDROXY-4-METHYLPENTYL)NORBOR- NADIENE ANDPROCESS FOR PREPARING SA'ME This application is a division of applicantscopending application Ser. No. 46l,703, filed on Apr. l7, 1974 now US.Pat. No. 3,886,289.

BACKGROUND OF THE INVENTION The present invention relates to2-(4-hydroxy-4- methylpentyl)norbomadiene and processes for preparingsame.

There has been considerable work performed relating to substances whichcan be used to impart (or enhance) flavors to (or in) various consumablematerials including foodstuffs. These substances are used to diminishnatural materials, some of which may be in short supply, and to providemore uniform properties in finished products. Authentic raspberry-typeflavor notes, particularly flavors having the aroma of full ripenedraspberries with the taste of the ripe fruit and its seedy, raspberrykernel note, are particularly desirable for uses in raspberry flavoringcompositions and food stuffs.

Fenarolis Handbook of Flavor Ingredients published by the ChemicalRubber Company of Cleveland, Ohio, (1971), sets forth on pages 666 and667 components of natural raspberry aroma and a recommended raspberryflavor. Although it is stated therein on page 666 that4-(p-hydroxyphenyl)-2-butanone exhibits the characteristic raspberrytaste and odor, there is no suggestion in this publication or any otherpublication in the prior art that there exist materials having the aromaof full ripened raspberries with a taste of the ripe fruit and itsseedy, raspberry kernel note.

Norbornane derivatives are known in the prior art for their uses inflavors and fragrances. Fenarolis Handbook of Flavor Ingredients, citedsupra, discloses at page 404 the flavor use of fenchyl alcohol 1,3,3,-trimethyl-Z-norbornanol) having the structure:

This compound is indicated to have a camphor-like odor with citrus notesand a bitter lime-like flavor. Norbornadiene(bicyclo-[2,2,1]hepta-2,5-diene) having the structure:

is disclosed as having a very diffusive, gassy-piney,camphoraceous-woody odor by Arctander, Perfume and Flavor Chemicals(Aroma Chemicals) 1969, Volume ll, No. 2387. The Arctander publicationstates that norbornadiene has occasionally been used in Pine needlefragrances to improve the diffusiveness of the fragrance, and to lendinitial power and short life to fragrances which are intended for shorteffect purposes".

The Arctander publication states that norbornadiene is produced byreaction of Cyclopentadiene and Acetylene in a Diels-Alder typereaction.

The following publications set forth the perfumery uses of compoundshaving the indicated structures:

US. Pat. No. 3,580,954 issued May 25, 1971 US. Pat. No. 3,780,109 issuedDec. 18, 1973 wherein R, represents hydrogen or methyl and R representslower alkyl.

US. Pat. No. 3,662,008 issued May 9, 1972 US. Pat. No. 3,673,261 issuedJune 27, l972 THE INVENTION For the purposes of our invention, theforegoing structure is intended to cover the dextro", laevo" and mixtureof dextro and laevo stereoisomers of The 2-(3-halo1propyl)-2,5-norbornadiene is then re 2-( yd yy p y l norborfladiene,acted with magnesium, thereby forming a Grignard rea The novel processfor the preparation of 2-(4- m h i h Structure;hydroxy-4-methylpentyl)norbornadiene of our inven tion involves fourreactions. to wit: 5

i. reacting cyclopentadiene with a S-halo-l-pentyne X such as5chloro'1-pentyne to form a 2-( 3-halo-li propyl]-2,5-norbornadiene suchas 2-( 3-chloro-l propyl)-2 5-norbornadiene according to the followingreaction: [0

C l Q ii. forming a Grignard reagent from the halopropyl wherein X iseither chloro or bromo. The formation of norbornadiene derivative; theGrignard reagent is carried out in the presence of iii. reacting theGrignard reagent with acetone to a solvent such as tetrahydrofuran ordiethyl ether. If form a Grignard complex; and necessary, the Grignardreaction is initiated using such iv. hydrolyzing the complex to form thedesired prodmaterials as methyl iodide.

uct. In the same reaction medium, preferably, this (irign Reactions(ii), (iii). and (iv) are illustrated by the folard reagent is thenreacted with acetone to form a lowing reaction sequence. Grignardcomplex having the structure:

0 WCI l2 om ct O WA NH4C1 The first reaction is preferably carried outusing a cy- X clopentadiene precursor, namely dicyclopentadiene a whichcan be handled more easily than cyclopentadiene itself and whichdecomposes to cyclopentadiene spontaneously during the reaction. Thereaction may be carried out in the presence of an inert solvent such astoluene. The mole ratio of cyclopentadiene: 5- chloro-l-pentyne ispreferably l:1. Although S-chlorol-pentyne is a preferred reactant,S-bromo-l-pentyne wherein X is defined as above. The reaction to formcan also be used and is to be considered within the this Grignardcomplex takes place at atmospheric presscope of our invention. Thereaction temperature range sure at reflux, and the temperature isdependant upon is IC200C; preferably l75l85C. The time Of the solventused, reaction varies from 10-20 hours depen ing p n h The ratio of thereactantzsolvent is of the order of temperature of reaction. Highertemperatures of reac- 60 1:5, lthough reactantzsolvent weight ratios of1:2 up give rise to Shorter required time for Completion of to 1:10 areworkable. The mole ratio of acetonefirig {he reaclioh- View of requiredtemperature range nard complex is preferably l:l, although an excess ofof reaction, it is required that this reaction be carried acetone isworkable, and molc ratios f t ;G j 0m in Pressure Vessel, anautoclavenard complex of 2:1 or higher are quite suitable.

At the termination 0f the reaction of the y p After formation of theGrignard complex. this Grign' diene Whh the p py acetylene the reamioh Pard complex is then hydrolyzed using weak acid, e.g. namely3413104Propyl)'2-5hOTbOmadiehe i5 ammonium chloride in saturated aqueoussolution. The

distilled under Vacuum using a fraclionafihg Columhmole ratio ofGrignard complex:weak acid is such that all of the Grignard complex isdecomposed or hydrolyzed.

At the termination of the reaction the desired product contained in thereaction mass is purified by first adsorbing it onto a material such assilica gel, separating the silica gel having the 2-(4-hydroxy-4-methylpentyl)norbornadiene adsorbed thereon from the rest of thereaction mass and washing it with a solvent such as hexane to remove anystarting materials present, e.g. unreacted dicyclopentadiene. The 2-(4-hydroxy-4-methylpentyl)norbornadiene is then removed from the silica gelby washing with solvent such as methanol. The2-(4-hydroxy-4-methylpentyl)norbornadiene methanol solution is thenconcentrated under reduced pressure yielding 2-(4-hydroxy4-methylpentyl)norbornadiene product which is in such purity and free ofreactants so that it can be used as a flavor ingredient.

When the 2-(4hydroxy-4-methylpentyl)norbornadiene of our invention isused as a food flavor adjuvant, the nature of the co-ingredientsincluded with said 2- (4-hydroxy-4-methylpentyl)norbornadiene informulating the product composition will also serve to alter theorganoleptic characteristics of the ultimate foodstuffs treatedtherewith. As used herein, in regard to flavors, the term alter in itsvarious forms means supplying or imparting flavor character or notes tootherwise bland, relatively tasteless substance or augmenting theexisting flavor characteristic where a natural flavor is deficient insome regard or supplementing the existing flavor impression to modifyits quality, character or taste".

As used herein, the term foodstuff includes both solid and liquidingestible materials which usually do but need not have nutritionalvalue. Thus, foodstuffs include soups, convenience foods, beverages,dairy products, candies, fruits, cereals, soft drinks, snacks and thelike.

Substances suitable for use herein as co-ingredients or flavoringadjuvants are well known in the art for such use being extensivelydescribed in the relevant literature. Apart from the requirement thatany such material be ingestibly acceptable and thus non-toxic orotherwise non-deleterious, nothing particularly critical resides inselection thereof. Accordingly, such materials which may in general becharacterized as flavoring adjuvants or vehicles comprise broadlystabilizers, thickeners, surface active agents, conditioners, otherflavorants and flavor intcnsifiers.

Stabilizer compounds include preservatives, e.g., sodium chloride,antioxidants, e.g., calcium and sodium ascorbate, ascorbic acid,butylated hydroxyanisole (mixture of 2 and 3 tertiarybutyl-4-hydroxyanisole), butylated hydroxy toluene(2,6-di-tertiary-butyl-4- methyl phenol), propyl gallate and the like,and sequestrants, e.g., citric acid.

Thickener compounds include carriers, binders, protective colloids,suspending agents, emulsifiers and the like, eg, agaragar; carrageenan;cellulose and cellulose derivatives such as carboxymethyl cellulose andmethyl cellulose; natural and synthetic gums such as gum arabic, gumtragacanth; gelatine, proteinaceous materials; lipids; carbohydrates;starches pectins, and emulsifiers, e.g., mono and diglycerides of fattyacids, skim milk powder, hexoses, pentoses, disaccharides, eg, sucrose,corn syrup solids and the like.

Surface a tive agents include emulsifying agents.

e.g., fatty acids such as capric acid. caprylic acid, palmitic acid,myristic acid and the like, monoand diglycerides of fatty acids,lecithin, defoaming and flavordispersing agents such as sorbitanmonostearate, potassium stearatc, hydrogenated tallow alcohol and thelike.

Conditioners include compounds such as bleaching and maturing agents,e.g., benzoyl peroxide, calcium peroxide, hydrogen peroxide and thelike; starch modi fiers such as peracetic acid, sodium chlorite, sodiumhypochlorite, propylene oxide, succinic anhydride and the like, buffersand neutralizing agents, e.g., sodium acetate, ammonium bicarbonate,ammonium phosphate, citric acid, lactic acid, vinegar and the like;colorants, e.g., carminic acid, cochineal, turmeric and curcumin and thelike; firming agents such as aluminum sodium sulfate, calcium chlorideand calcium gluconate; texturizers; anti-caking agents, e.g., aluminumcalcium sulfate and tribasic calcium phosphate; en zymes; yeast foods,e.g., calcium lactate and calcium sulfate; nutrient supplements, e.g.,iron salts such as ferric phosphate, ferrous gluconate and the like,riboflavin, vitamins, Zinc sources such as zinc chloride, zinc sulfateand the like.

Other flavorants and flavor intensifiers include or ganic acids, e.g.,acetic acid, butyric acid, caproic acid, caprylic acid, formic acid,Z-Hexenoic acid, 3- Hexenoic acid, isobutyric acid, isovaleric acid,propionic acid, and valeric acid; Ketones and aldehydes, e.g.,acetaldehyde, acetone, acetyl methyl carbinol, acrolein, diacetyl,B,/3-Dimethylacrolein, Hexanal, 2- Hexenal, cis-3-Hexenal, 4(p-Hydroxyphenyl)- 2- butanone, oz-lonone, B-lonone, and Z-Pentenal;alcohols, such as l-Butanol, trans-2Buten-l-ol, Ethanol, Geraniol,lHexanol, cis-3-Hexen-l-ol, 3Methyl-3- buten-l-ol, l-Pentanol,l-Penten-3-ol; esters, such as Butyl acetate, Ethyl acetate, Ethylbutyrate, Ethyl crotonate, Ethyl propionate, 2-Hexenyl acetate,Z-Hexenyl butyrate, Hexyl acetate, Hexyl butyrate, lsoamyl ace tate,Isopropyl butyrate, Methyl butyrate, Methyl caproate, Methyl caprylate,Propyl acetate, Amyl acetate, Amyl butyrate, Benzyl salicylate, Dimethylanthranilate, Ethyl methylphenylglycidate, Ethyl succinate, lsobutylcinnamate and Terpenyl acetate; Essential Oils such as Jasmine absolute,Rose absolute, Orris absolute, Lemon essential oil and Vanilla;lactones; sulfides, e.g. methyl sulfide and other materials such asMaltol and Citral, as well as natural raspberry oil.

The specific flavoring adjuvants selected for use may be either solid orliquid, depending upon the desired physical form of the ultimateproduct, i.e., foodstuff, whether simulated or natural, and should, inany event, be capable of providing an environment in which the2-(4-hydroxy-4-methylpentyl)norbornadiene can be disbursed or admixed toprovide a homogeneous medium. In addition, selection of one or moreadjuvants, as well as the quantities thereof, will depend upon theprecise organoleptic raspberry character desired in the finishedproduct, Thus, in the case of flavoring compositions, ingredientselection will vary in accordance with the foodstuff to which the flavorand aroma are to be imparted. In contradistinction, in the preparationof solid products, e.g., simulated foodstuffs, ingredients capable ofproviding normally solid compositions should be selected such as variouscellulose derivatives,

As will be appreciated by those skilled in the art, the amount of2-(4hydroxy-4-methylpentyl) norbornadiene employed in a particularinstance can vary over a relatively wide range whereby its desiredorganoleptic effects (having reference to the nature of the product) areachieved. All parts and percentages given herein are by weight unlessotherwise specified. Thus, correspondingly greater amounts would benecessary in those instances wherein the ultimate food composition to beflavored is relatively bland to the taste, whereas relatively minorquantities may suffice for the purposes of enhancing the compositionmerely deficient in natural flavor or aroma. Thus, the primaryrequirement is that amount which is effective. i.e., sufficient to alterthe organoleptic characteristics of the parent composition, whetherfoodstuff per se or flavoring composition. Thus. the use of insufficientquantities of 2-(4-hydroxy- 4-methylpentyl)norbornadiene will, ofcourse, substantially vitiate any possibility of obtaining the desiredresults while excess quantities prove needlessly costly and in extremecases, may disrupt the flavor-aroma balance, thus provingself-defeating. Accordingly, the terminology effective amount" andsufficient amount is to be accorded a significance in the context of thepresent invention consistent with the obtention of desired flavoringeffects.

Thus and with respect to ultimate food compositions, it has been foundthat quantities of 2-(4-hydroxy-4- methylpentyl)norbornadiene rangingfrom a small but effective amount, e.g., 0.02 parts per million up toabout 50 parts per million by weight based on total composition aresuitable. Concentrations in excess of the maximum quantity stated arenot normally recommended since they fail to provide commensurateenhancement of organoleptic properties. in those cases wherein the 2-(4-hydroxy-4-methylpentyl)norbornadiene is added to the foodstuff as anintegral component Reaction of the flavoring composition, it is, ofcourse, essential that the total quantity of flavoring compositionemployed be sufficient to yield an effective 2-(4-hydroxy-4-methylpentyl)norbornadiene concentration in the foodstuff product,

Food flavoring compositions prepared in accordance with the presentinvention preferably contain 2-(4 hydroxy-4-methylpentyl)norbornadienein concentra tions ranging from about 0.05% up to about 10% by weightbased on a total weight of said flavoring composition.

The compositions described herein can be prepared according toconventional techniques well known as typified by cake batters and fruitjuices and can be formulated by merely admixing the involved ingredientswithin the proportions stated in a suitable blender to obtain thedesired consistency, homogeneity of disper sion. etc.. Alternatively,flavoring compositions in the form of particulate solids can beconveniently prepared by admixing the2(4-hydroxy-4-methylpentyl)norbornadiene with, for example, gum arabic,gum tragacanth. carrageenan and the like and thereafter spraydrying theresultant mixture whereby to obtain the particulate solid product.Prepared flavor mixes in powder form e.g., a raspberry flavored powderare obtained by mixing dried solid, components, e.g., starch. sugar andthe like and 2-(4-hydroxy-4-methylpentyl) norbornadiene in a dry blenderuntil the requisite degree of uniformity is achieved.

It is presently preferred to combine the 2-4-hydroxy-4-methylpentyl)norbornadiene with the following adjuvants:

Parahydroxybenzyl acetone Vanillin Maltol a-lonone B-lonone lsobutylacetate Ethyl butyrate Dimethyl sulfide Acetic acid Acetaldehyde4-(2,6,6-trimethyl-l ,3-cyclohexadienl-yl)-2- butanone 4-(6,6-dimethyl-2-methylene-3-cyclohexenl -yl )-2- butanone The followingexamples are given to illustrate embodiments of our invention as it ispresently preferred to practice it. It will be understood that theseexamples are illustrative, and the invention is not to be considered asrestricted thereto except as indicated in the Zip pended claims.

EXAMPLE 1 PREPARTATION OF 2-(3-CHLORO-1-PROPYL)-2,5-NORBORNAD1ENE Amixture of grams of dicyclopentadiene, grams of 5-chloro-l-pentyne, 10grams toluene, and 1 gram lonol is stirred in a 300 ml autoclave at Cfor 16 hours. The autogenous pressure during the reaction is 2050 psig.The reaction mass from the autoclave is distilled under reduced pressureto give 19 grams of material, bp 8894C, at 14 mm Hg which containedapproximately 45% 2-( 3-chloro l -propyl )2 ,5- norbornadiene accordingto GLC 10 ft. X 1/8 in., 5% 0V l0l,lOO-200C at 10c/min.). The remainderis a mixture of dimers and trirners of cyclopentadiene. The structure isconfirmed by mass spectroscopy (m/e 168,105,91 ,77,66,39,27).

lonol is a registered trademark identifying the compound,2,6-di't-butyl-4-methy1 phenol.

EXAMPLE ll PREPARTION OF 2-( 4-HYDROXY-4METHYLPENTYL NORBORNADIENEReaction Cl m g Ci AA/ NH Cl 2-(3-chloro-l-propyl)norbornadiene (10 g,45% by GLC) is added to 0.7 grams of magnesium turnings and 30 ml ofdiethyl ether. In order to initiate the reaction. a few drops of methyliodide is added and the ether is distilled off while adding 25 ml oftetrahydrofuran. The resulting mixture is stirred at reflux for 2.5hours. Acetone (l0 grams) is added and the mass is refluxed anadditional 30 minutes. The resulting Grignard complex is decomposed byaddition of 5 ml of saturated ammonium chloride solution. The organiclayer is distilled to give 4.5 grams of material, bp 100C at l.5 mm Hgwhich is a mixture of the desired product and dicyclopentadiene. Themixture is dissolved in l0 ml of hexane and stirred for approximately 30minutes with grams of silica gel to adsorb the tertiary alcohol. Themixture is filtered and the silica gel is washed with hexane to removeall of the dicyclopentadiene. The 2-(4-hydroxy-4-methylpentyl)-norbornadiene is then removed from the silica gel bywashing with several 10 gram portions of methanol. The methanol isremoved under reduced pressure to give Zgrams of 2(4-hydroxy-4-methylpentyl)-norbornadiene.

EXA MPLE llI RASPBERRY FLAVOR The following formulation is prepared:

Ingredient Parts by Weight para-hydroxybenzyl acetone 4 vanillin lmaltol 2 oeionone I09? in propylene glycol) 2 isohutyl acetate ethylhutyrate 5 dimethyl sulfide l acetic acid H] acetaldehyde l5 propyleneglycol J40 l m ce EXAMPLE IV The following mixture is prepared:

Ingredients Parts by Weight Natural Raspberry Concentrate Juice 2 /z7oWater Sugar syrup (37.5 Baume) l2'k% The ripened raspberry and seedy,raspberry kernel note of this raspberry juice is imparted in increasedstrength by addition of 2-(4-hydroxy-4-methylpentyl)- norbornadiene atthe rate of from 0.02 parts per million up to l0 parts per million.

EXAMPLE V To the raspberry formulation of Example [[1, 2-(4-hydroxy-4-methylpentyl)norbornadiene at the rate of 0.2% is added. Thismaterial is then called the test composition". The raspberry formulationwithou 2-(4- hydroxy-4-methylpentyl)norbornadiene is called the controlcomposition".

The test and control compositions are added to the food productsdescribed hereinafter in the proportions shown for l0 kilograms ofmaterial to be flavored:

Pudding Cooked sugar l5-20 grams (.l52%) Cooked sugar [00 ml of sugarsyrup (prepared by dissolving l kilogram of sucrose in 600 ml of water)and 20 grams of glucose are mixed together and slowly heated to l45C.The flavor is added and the mass allowed to cool and harden.

Pudding To 500 ml of warmed milk are added with stirring a mixture of 60grams sucrose and 3 grams of pectin. The mixture is boiled for a fewseconds and the

1. 2-(4-HYDROXY-4-METHYLPENTYL) NORNADIENE HAVING THE STRUCTURE: